This invention relates to new and useful imide derivatives of principal interest to those in the field of medicinal chemistry and/or chemotherapy. More particularly, it is concerned with a novel series of spiro-imide compounds, which are of especial value in view of their ability to effectively control certain chronic complications arising from diabetes mellitus (e.g., diabetic cataracts, retinopathy and neuropathy). The invention also includes a new method of therapy within its scope.
In the past, various attempts have been made by numerous investigators in the field of organic medicinal chemistry to obtain new and better oral antidiabetic agents. For the most part, these efforts have involved the testing of various organic compounds in an endeavor to determine their ability to lower blood sugar (i.e., glucose) levels. However, in the search for newer and still more effective antidiabetic agents, little is known about the effect of other organic compounds in preventing or arresting certain chronic complications of diabetes, such as diabetic cataracts, neuropathy and retinopathy, etc. Nevertheless, K. Sestanj et al. in U.S. Pat. No. 3,821,383 do disclose that certain aldose reductase inhibitors like 1,3-dioxo-1H-benz[d,e]isoquinoline-2(3H)-acetic acid and some closely-related derivatives thereof are useful for these purposes even though they are not known to be hypoglycemic. These compounds function by inhibiting the activity of the enzyme aldose reductase, which is primarily responsible for catalyzing the reduction of aldoses (like glucose and galactose) to the corresponding polyols (such as sorbitol and galactitol) in the human body. In this way, unwanted accumulations of galactitol in the lens of galactosemic subjects and of sorbitol in the lens, retina, peripheral nervous system and kidney of various diabetic subjects are thereby prevented or reduced. As a result, these compounds control certain chronic diabetic complications, including those of an ocular nature, since it is already known in the art that the presence of polyols in the lens of the eye quite often leads to cataract formation and concomitant loss of lens clarity.